The website PoliticMo.com captured audio from a Saturday night fundraiser of Akin telling supporters that McCaskill goes to Washington, and, like a game of "fetch," brings home red tape, bureaucracy and executive orders. Akin says a senator should "bless" Missouri with solutions instead of more problems.

McCaskill did not immediately comment.

The two are locked in a fierce battle for the Senate. Republicans are still searching for the four seats the party needs to win the Senate majority. Akin has gotten in trouble before with women voters and members of his own party for comments he made about "legitimate rape."